Japanese Utility Model Application Disclosure Gazette (Kokai) No. Hei1-141707, Japanese Utility Model Application Disclosure Gazette (Kokai) No. Hei2-84623 and Japanese Patent Application Disclosure Gazette (Kokai) No. Hei9-51913 disclose a disposable diaper including grooves extending through a thickness of a liquid-absorbent core or grooves dividing the liquid-absorbent core in a plurality of sections in the transverse direction of the absorbent core. Along these grooves, a topsheet and a backsheet of the diaper are bonded to each other to define bottoms of the respective grooves.
Japanese Utility Model Application Publication (Kokoku) No. Hei5-39691 and Japanese Patent Application Disclosure Gazette (Kokai) No. Hei9-108262 disclose a sanitary napkin having a liquid-absorbent core compressed in the direction from a topsheet toward a backsheet or in the reverse direction to form grooves extending in the longitudinal direction of the napkin. The liquid-absorbent core presents a remarkably high density along bottoms of the grooves.
In the prior art article described above, when the topsheet and the backsheet are bonded to each other to define the bottoms of the respective grooves, an amount of body fluids that has flown into the grooves might stay and gives a wearer of the article, such as a diaper, a feeling of wetness causing the wearer's discomfort. The reason is that the liquid-absorbent core of a disposable diaper or a sanitary napkin generally has a limited thickness and the side walls of the grooves are correspondingly limited in a total surface area even if the grooves are intended to absorb the amount of body fluids flowing therein.
FIG. 7 is a sectional view showing a transverse cross-section of a napkin 101 described in the Japanese Utility Model Application Publication Gazette (Rokoku) No. Hei5-39691. The napkin 101 solves the above problem, i.e., prevents body fluids from staying in grooves 102 by placing portions of a liquid-absorbent core 104 under bottoms 103 of the respective grooves 102. However, the portions of the liquid-absorbent core 104 immediately underlying the bottoms 103 have been compressed to have relatively high density and rigidity of the core 104 is correspondingly high in these portions. To alleviate an adverse effect of the relatively high density, opposite side walls 106 of the respective grooves 102 are tapered toward the bottoms 103 to define a U- or V-shaped section of the liquid-absorbent core 104 in the vicinity of each groove 102.
The napkin 101 of FIG. 7 formed on both side regions with such grooves 102 can not smoothly placed against a crotch region of the wearer with the napkin 101 being curved over its full width substantially in an inverted U-shape. In an inverted embodiment of the napkin 101 of FIG. 7, the napkin may be formed on its both side regions with grooves by compressing the napkin from the backsheet toward the topsheet to facilitate the napkin to crook or curve over its full width substantially in an inverted U-shape. However, there is still an apprehension that the bottoms of the respective inverted grooves, having a relatively high rigidity, might directly stimulate soft skin in the wearer's crotch region. In addition, it is impossible for such a napkin to offer the desired function and effect of preventing body fluids from leaking sideways by receiving and absorbing an amount of the body fluids, flowing on the topsheet transversely of the napkin, in the grooves.